1. Field of the Invention
The present invention relates to a gas device and, particularly, to a gas device that provides more visible flames and that is safe.
2. Description of the Related Art
Heat devices can be classified into two groups —one is electrical and the other is non-electrical. Each group has advantages and disadvantages. A device, which generates heat via combustion of combustible materials, is generally more effective and does not place a heavy burden on an electricity supplying system. Electrical heat devices or non-electrical heat devices such as fireplaces and firepits are both available on the market. Generally, a heat device that generates heat via combustion of combustible materials is used not less often than that via electricity in places in high latitude, and such heat device is popularly used at outdoor places. An electrical heat device normally includes a high-load electrical unit and a heat pipe system. Consequently, electrical heat devices are costly and consume electrical power, and there is a matter of concern about a supply of high-load electrical current. Therefore, electrical heat devices are used more at offices and less at home, and fireplaces are used more to heat homes, in middle and high latitudes, especially countries in high latitude. It is convenient and cheaper to use fireplaces. Typically, combustible materials include cordwood, pellet, propane, or natural gas. Natural gas, when concerning the environmental protection issue, is the cleanest combustible material as it produces the least carbon dioxide per unit of heat energy. On the contrary, wood is a combustible material which is less environmental friendly. In 2012, 70 percent of fireplaces sold in North America use natural gas as a combustible material. In addition, more people are in the market for flame heat devices that not only generate heat, but also are decorative and aesthetic.
Presently, gas flame heat devices, by distributing nozzles or a transparent shield as a fluid guide structure to induce outside airflow due to the “chimney effect”, control and change the shape of flames. Commonly, a shield is disposed above a gas flame heat device, and, therefore, the gas flame heat device is half closed. In addition, when a flame is a vortex flame, flames of different shapes are different in an upward axial direction. It is difficult to change a vortex flame in a transverse direction of the flame. Problems usually associated with a gas flame device are that the size of a flame is limited, that gas is easily accumulated, or that the gas flame heat device gets hot. Although the shield can prevent outside airflow to disturb a flame and allow the flame to remain stable, ventilation becomes a problem. Therefore, the gas flame heat device gets hot. Since the shield is provided to shelter the flame, it typically includes a distal end thereof defining a free end and delimiting an opening allowing ventilation. The size of opening of the shield is critical. If the size of opening is big, the shield can not effectually shelter the flame. If the size of opening is small, problems of poor heat and of exhaust gas dissipations can occur despite that the flame can remain stable. Even worse, the flame will extinguish and an incomplete combustion would occur due to a fresh air deficiency. The incomplete combustion will result in soot and poisonous gas. Furthermore, the flame heat device suffers poor heat dissipation if fresh airflow is deficient. Consequently, the longer the flame burns, the hotter the gas flame device becomes.
Without using the shield to guide fluid, changing ways of distributing nozzles is another way to control a flame. Unfortunately, it becomes easy that outside air disturbs the shape of flame, the flame becomes uncontrollable, and the shape of flame changes limitedly.
Recently, a method to control a flame electromagnetically is devised, but such method adopts a complex and costly device and is limited to control a small scale flame only. The device is still in the experimental stages and not on the market. Likewise, if no shield is used, the flame is susceptible to disturbance by outside air.
U.S. Pat. No. 7,097,448 shows a vortex type gas lamp for producing an upwardly directed vortex flame inside a surrounding and confined boundary of a rotating body of air. An interface is located between the body of air which is devoid of gas and a central region of gas which is bounded by the interface during the operation of the gas lamp. Combustion occurs inside the interface. The gas lamp has a central axis and includes a base supplying combustible gas without air at and nearly adjacent to the central axis. A shield includes first and second axially extending sections structurally attached to the base in a fluid sealing relationship. The first and second sections of the shield are substantially identical and transparent to light, and each includes an impermeable wall having an arcuate inner surface and an arcuate outer surface. Each of the first and second sections of the shield has first and second edges extending axially. The gas lamp further includes first and second walls alternately overlapping one another. The first and second walls are adjacent to their edges and spaced from one another and form tangentially directed ports, thereby forming an axially extending mixing chamber open at its side only through the ports. The first and second sections of the shield at the base surround the entry of combustible gas and receive air for combustion only through the ports. Whereby, a flame results from the combustion process is spaced from the inner surfaces, and the peripheral body of air is devoid of gas entering through the ports. In use, fresh air from outside can enter the gas lamp through the ports to keep the flame alive. In reality, the ports can not prevent excess air from entering the chamber to greatly disturb the height and the swirling shape of the flame. Accordingly, the flame from the gas lamp is kept within a scale in order to have a swirling shape. However, the top surface of the base can become too hot to touch as no airflow cools the base. Also, the flame will not have an obvious swirling shape if its scale is small. The flame will not have an obvious swirling shape if the shield is not tall enough. The combustible gas accumulates on the base easily, because it has a greater density than air. If the combustible gas and air become mixed in adequate concentrations and the gas has a higher concentration, a flash fire can occur, and if the combustible gas and air become mixed in adequate concentrations and the gas has a lower concentration, it is difficult to ignite such gas and air mixture. To avoid the risks, a continuous and automatic stopping electronic ignition device is a solution, but incurs high costs. In contrast to a gas lamp that is manually controlled, a gas lamp equipped with a continuous and automatic stopping electronic device is more pricey.
U.S. Design Pat. No. 621,873 shows a fire tornado lamp. A base includes a plurality of ports disposed circumferentially. A shield is transparent to light and hollow and includes a passage. The base and the shield are connected to each other. Each port extends radially with respect to and is in communication with the passage. Each port is configured to induce air into the passage in a direction substantially tangential to a circumference of the passage. Problems are that the ports can not prevent excess air from entering the passage to disturb a flame from the lamp and that the longer the flame burns the hotter the base becomes. A continuous and automatic stopping electronic device may be used to avoid a flash fire risk, but incurs high costs. In addition, air is guided to flow above the bottom of the flame at an angle perpendicular to a flame burning direction.
TW Pat. No. M461769 shows an outdoor use flame heat device. A gas distribution chamber includes the top thereof including a plurality of burner holes and is disposed on a base. A shield is disposed above the flame heat device. An air distribution chamber is disposed between the gas distribution chamber and the shield. A plurality of air holes is distributed around the shield. A glass tube is disposed in the shield and above the plurality of burner holes and the air distribution chamber. It is claimed that the glass tube allows gas and air fully mixed for combustion, that flames can cooperate together to form a net to increase thermal efficiency, and that the flames in the glass tube can extend higher due to the “chimney effect”. In reality, wind can blow directly to the burner holes and, therefore, affects the combustion and the shape of the flames. The glass tube makes the ignition timing difficult. If the timing is wrong, flames become turbulent. Only a small amount of outside air flows into the flame heat device, so the longer the flames burn the hotter the flame heat device and the glass tube become. If the ignition timing is too late or if failure of ignition happens, gas will accumulate on the bottom of the flame heat device easily. Therefore, the flame heat device carries risks that the gas has a higher concentration than that of the air and that flash flames occur. To avoid the risks, a continuous and automatic stopping electronic ignition device is a solution, but incurs high costs. In addition, the flame heat device is similar to the above two references in that the bottom thereof is a semi-closed end. A semi-closed area is formed by the plurality of air holes and an end of the glass tube disposed adjacent to burner holes.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.